


Three to Tango

by Brynncognito



Category: Sherlock (TV), Sherlock Holmes & Related Fandoms
Genre: Anal Sex, Angst, Asexual Character, Asexual Sherlock, Asexuality, Bisexual Character, Bisexual John, Bisexual Male Character, Bisexuality, Condoms, Cunnilingus, Developing Relationship, Explicit Sexual Content, F/M, Fluff, Fluff and Angst, Fluid Sexuality, M/M, Multi, Open Marriage, Open Relationships, Oral Sex, Pansexual Character, Pansexual Mary, Penis In Vagina Sex, Platonic Female/Male Relationships, Platonic Relationships, Polyamory, Porn With Plot, Porn with Feelings, Queerplatonic Relationships, Safer Sex, Shameless Smut, Sherlock Series 3 Spoilers, Threesome - F/M/M, Vaginal Sex
Language: English
Status: In-Progress
Published: 2014-01-02
Updated: 2014-02-22
Packaged: 2018-01-07 04:06:16
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 12
Words: 14,608
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/1115300
Author URL: https://archiveofourown.org/users/Brynncognito/pseuds/Brynncognito
Summary: <blockquote class="userstuff">
              <p>It surprises Sherlock, how little he minds Mary’s presence in John’s life.</p>
            </blockquote>





	1. Chapter 1

**Author's Note:**

> Written in part for [equalseleventhirds](http://equalseleventhirds.tumblr.com/), who gave me the idea when I said I really needed more unapologetically bisexual John. Many thanks to [myaudiocommentary](http://myaudiocommentary.tumblr.com/), [goldenheartedrose](http://goldenheartedrose.tumblr.com/), [youhavereachedsamsblog](http://youhavereachedsamsblog.tumblr.com/), [and equalseleventhirds](http://equalseleventhirds.tumblr.com/) for the beta reading and input, and [sassinassassin](http://sassinassassin.tumblr.com/) for the brit-pick. If there's anything else in the way of mistakes and awkwardness folks see, feel free to point it out!
> 
> Other than that, enjoy my shameless OT3 fic.

It surprises Sherlock, how little he minds Mary’s presence in John’s life. He’s not used to this feeling of ambivalence-bordering-on-appreciation. Most of John’s exploits _before_ had been rather deserving of Sherlock’s scorn, in his humble opinion. Mary, though, is different.

Mary Morstan is clever. She’s not quite as clever as he is, of course, but if _that_ were the criterion by which Sherlock judged John’s partners, no one would _ever_ be good enough for _his_ blogger. But it isn’t just her cleverness that Sherlock appreciates. She has a particular type of humour about her, and a quiet self-assurance that means she’s never once displayed any real jealousy of he and John’s time together, that he’s seen.

Perhaps the strangest part of all is the fact that Mary _likes_ him, according to John. She’s actually expressed these feelings aloud, even.

No, wait, Sherlock knows what’s even stranger than the fact that she likes him: It’s the realisation that he feels the same way.

Overall, Sherlock’s decided, he’ll tolerate Mary’s presence in John’s life. Particularly as John’s always made it so very clear that he wouldn’t be interested in _him._

 * * * * * * * * * * * *

It isn’t that Sherlock’s disinterested in sex, per se, simply that he’s disinterested in the idea of having sex with the vast majority of people. He considers himself asexual, though he does still find it necessary to bring himself to orgasm frustratingly often and has been known to pick men up at the bar to quell his body’s urges.

Mostly, Sherlock gets by with a quick wank once every week or two, and a shag about half as frequently. His body doesn’t quite seem to know _how_ to react, however, the first time he hears John and Mary.

Obviously it’s not _intentional,_ that he’s let himself quietly into their flat at the exact moment they’re having flash-slappingly, _shoutingly_ enthusiastic sex. Sherlock had simply meant to snag one of John’s jumpers for an experiment and duck right back out. There’s no mistaking the feminine gasps and more masculine growls for anything other than what it is, though, and Sherlock absolutely freezes.

There’s a moment, after he realises what he’s nearly interrupted, when his body can’t decide if the majority of his blood flow should suffuse his cheeks with an embarrassed flush or flow in a distinctly more southern direction. He doesn’t even give it the chance to make up its mind before he’s swearing under his breath, dashing straight back out the front door and locking it again.

Sherlock doesn’t let himself think until he’s safe inside 221b, leaning heavily against the door that separates the flat from the rest of the place with eyes closed and heart hammering fit to burst free of his ribcage.

_Bugger._

* * * * * * * * * * * *

Like most things Sherlock doesn’t care to sort through, the accidental eavesdropping incident is firmly wiped from Sherlock’s hard drive. He’s managed to do it so thoroughly, in fact, that he’s confused and somewhat alarmed by the symptoms of nerves he’s noticed have popped up around John. But there are cases to be solved and blog posts to be mocked, so he simply wipes his sweaty palms on his trousers perfunctorily and grinds his teeth half into oblivion as he tries to will his hands to stop shaking long enough so he can finish adjusting his microscope.

A few times, John asks Sherlock if he’s all right, because he may not be a consulting detective, but he knows his best friend well enough. When Sherlock brushes off his concern for the third or fourth time, though, John finally throws up his hands and gets up to grab his jacket.

Sherlock only lifts his gaze from the microscope after the door’s closed a little too loudly behind John.

He won’t even let himself entertain the possibility of going after him.

* * * * * * * * * * * *

Despite Sherlock’s hasty deletion and his unconscious altered behaviour around John, things manage to go pretty much back to normal, or at least “normal” as it exists in this new world where John has a wife in his life, as well. They settle a few cases together, which John writes up in his usual painfully constructed fashion, and Mary even tags along on a couple.

Of course, only a couple months have passed in this fashion before _it_ happens.

They’re on a case again, the three of them, though Sherlock’s mostly just scoping the pub out for potential suspects or _anything_ useful he can pick up there. John and Mary aren’t taking things all that seriously, probably as it’s a theft rather than a kidnapping or murder, and they’ve been murmuring and giggling across the table for at least ten minutes, his fingers tapping against the table in increasing agitation, by the time Sherlock finally lets out a noise of exasperation.

“Must you engage in your childish _gossip_ or whatever drivel you’re on about _now?”_ Sherlock snaps. John’s expression immediately drops into the face that he reserves for when Sherlock’s _really_ pissed him off, but Mary seems more bemused than anything.

“John, it’s perfectly all right,” Mary assures her husband, with a pat on the hand that’s almost condescending but still seems to calm him down. “Sherlock’s our friend, so _I_ don’t see we can’t let him in on our little secret.”

Sherlock’s brow furrows and John opens and closes his mouth momentarily before sighing and giving in to his wife’s wishes, as he often does.

“Right,” John replies, clearing his throat and squaring his shoulders the way he always does when he’s about to do something unpleasant. “Mary and I are in... an open relationship. Mostly sexually. And we’ve been trying to sort out whether there’s anyone here we both fancy enough to invite home for a little bit.” John licks his lips, addressing a space somewhere off to the left of Sherlock rather than speaking to him properly. “We’ve had a few women now, but it’s been a while since I’ve been with a bloke, and we were trying to decide if the businessman over in the corner would be worth approaching or not.”

Sherlock’s struck absolutely speechless, for a span long enough that John starts to look a little worried and uncomfortable. Before he can open his mouth again, though, Sherlock blurts the first thing that comes to mind.

“But you’re not _gay.”_

John frowns, looking almost disappointed or annoyed, Sherlock’s not sure which.

“Of course I’m not _gay,_ Sherlock. I like women, you know that. I’m bisexual. Just haven’t always found blokes I fancy well enough to shag or date, at least not any since the army.”

Sherlock’s well and truly shell-shocked by this revelation, to the extent that Mary actually looks a little _worried_ about him.

“John, did you _really_ never tell him you were bi?”

 _“No,_ he rather neglected to mention that fact,” Sherlock responds sharply, finally coming to his senses. Case forgotten (it wasn’t that interesting, anyway), he rises to leave, sliding his Belstaff on and wrapping it around himself in a manner he knows appears defensive even to the unobservant eye.

“Well, then I suppose he also neglected to mention the _horrid_ crush he’s had on you for ages… and the small one I’ve developed,” Mary adds slyly. There’s something devious in the way she looks at Sherlock, and he pauses in the act of straightening his coat to stare.

“What… she means is…” Here John pauses, taking a deep, fortifying breath before continuing determinedly, like the soldier he is. “Would you like to join us in bed?”

The degree to which Sherlock suddenly realises he _needs_ this takes him entirely by surprise. Does John really expect him to say anything but yes?


	2. Chapter 2

**Summary for the Chapter:**

> An aborted bedroom visit.

It’s only the casual familiarity with which John and Mary leads Sherlock back to their flat, then toward the bedroom, that keeps Sherlock’s panic in check. As it is, his heart’s thrumming at a hummingbird rate, and his mouth’s gone absurdly dry.

“Sherlock?” John’s voice interrupts Sherlock’s impending panic attack, and he blinks rapidly before focusing on the worried face of his best friend.

“Hm?” Sherlock’s bone-rumbling voice has gone high with anxiety, and he can’t keep _still._ It’s no wonder, then, that John and Mary are both looking at him with concern, still fully dressed.

“We don’t have to do this, you know.” It’s Mary speaking, this time, and Sherlock’s head jerks too-sharply in her direction.  “I don’t want you to feel pressured to do something you’re uncomfortable with, Sherlock.” When Sherlock bristles, offended at the suggestion that anyone could coax him into doing something he doesn’t really want, she offers him a wry smile.

“I’m sure if you didn’t want this on some level, we wouldn’t be here at all,” Mary continues, soothing Sherlock’s ego somewhat. John’s just nodding, arms crossed as he lets his wife be the voice of reason for once. It’s been nice, having someone else around to keep Sherlock from doing anything too ridiculous.

_“Obviously,”_ Sherlock sniffs. He’s still tense, though, fingers tapping restlessly against his thighs in a manner he doesn’t even seem to realise he’s doing. He must be really nervous, then, if he’s lost his iron-tight grip on his own behaviour.

“What Mary’s trying to _say,_ Sherlock,” John interrupts, his voice gentle, but firm enough that Sherlock won’t cut him off with some snide comment, “is that while we’re both sure you wouldn’t be here unless you wanted to be, there’s no reason we _have_ to fall right into bed together.” Now it’s Mary nodding, her expression softened to match John’s voice. Sherlock’s stomach roils in an unfamiliar fashion. He’s not _used_ to being handled so gently, and he’s not sure whether he likes it or not.

“Why shouldn’t we ‘fall right into bed together’?” There’s something in Sherlock’s voice that suggests he’s genuinely puzzled or curious, not just being belligerent for the sake of it. “I’m hardly new to sex, whatever Moriarty might think. I may not engage in it very frequently, but I’m still far from inexperienced.”

Sherlock’s watching John carefully enough that he sees something cross his friend’s face that’s almost… pity. And he _really_ doesn’t think he likes it.

“Forget it,” Sherlock snaps abruptly, turning to leave. _This was a mistake. Stupid, stupid, stupid._

“Sherlock--” John’s reaching for him, but Sherlock jerks away before his fingers quite reach him, and he lets his hand fall.

“John.” Mary’s lips form her husband’s name in a way that makes the single syllable an entire monologue. Or maybe it’s the look they exchange that makes Sherlock sure they’re having some private _married_ conversation without speaking a word aloud. His face heats, and he swiftly turns toward the door before his flush can betray him.

 “We’ll talk about this later, yeah?” John’s addressing Sherlock, who simply gives a curt nod and lets himself out of the bedroom, then the flat itself a moment later.

* * * * * * * * * * * *

What the hell was he _thinking?_ Sherlock growls as he shoves his hands deep into his coat pockets, striding briskly in the general direction of Baker Street rather than catching a cab. There’s no way he could sit still long enough to ride in one.

Sherlock’s mind is racing through scenarios at the speed of light, tearing into itself the way it normally only does when he’s not been on a case for weeks. Before he quite realises it (a true testament to how wrapped up in the problem of John-and-Mary he’s become), he’s nearly to the area of town where his old dealer tends to skulk.

For a moment, the familiar itch is all Sherlock can think about. It’s been so long since he’s experienced the high that only cocaine can produce, and his heart rate quickens with the temptation. In the end, though, he stops off to buy a carton of cigarettes instead, and he’s gone through half of it by the time he reaches Baker Street, one after another after another.

There’s no mistaking the smell of cigarette smoke on him, and Mrs. Hudson tsks as she takes in not only that, but the haggard sort of look on his face.

“Not _now,_ Mrs. Hudson,” Sherlock growls when it becomes clear she’s about to lecture him for his smoking habit, and though she makes a small sound like she’s offended or hurt that he won’t let her mother him, she at least lets it go for now.

Finally, Sherlock’s safe in the familiar flat that he’d once shared with John. He comes to a halt, though, unsure what he actually wants to _do_ now that he’s here.

The shower’s calling his name, he decides at last (not literally, of course), and he marches off in that direction, though he holds little hope it will clear his muddled thoughts.

 


	3. Chapter 3

**Summary for the Chapter:**

> A decision is made.

It’s nearly a full 48 hours hour later that Sherlock comes a decision about how to handle this new, complicated _thing_ he’s fallen into with John and Mary. During that period, he’s of course ignored countless text messages and phone calls from the pair of them, two separate emails, and at least one visit to 221b where he’d firmly told Mrs. Hudson that he wasn’t there and wasn’t to be bothered.

Sherlock deletes all the texts, emails, and voicemails without much absorbing their contents, though he’s aware they contain increasing levels of both worry and annoyance. Sherlock _ignoring_ John is nothing new, but he’s never really ignored him for something so important before.

Rather heedless of what his solid wall of silence might have done to John or Mary, or his _relationship_ (friendship?) with the both of them, Sherlock finally sends off a single text message to the pair.

_221B Baker Street. Come at once if convenient._   
_If inconvenient, come anyway. SH_

With a faint smile threatening to slip onto his face at any moment, Sherlock launches himself from his armchair and enters the kitchen, where he starts loudly making tea. The irony of his choice of kettle and china (the exact same he’d once used for a visit from a particular consulting criminal, in fact) is far from lost on him, but he decides to ignore it.

It takes Sherlock a bit more time than he’d like to hunt down a package of biscuits that hasn’t gone stale or mouldy. Now that he’s living here alone, there’s usually more body parts than food in the flat, save for what Mrs. Hudson picks up and what _Mycroft_ tries to force on him.

Sherlock’s just arranged things nicely with the contents of a package of chocolate digestives that he’s sure was Mrs. Hudson’s doing when the door below crashes open and two pairs of feet scramble madly up the stairs to do the same to the door there.

John looks positively wild with adrenaline-riddled panic, and Mary’s in much the same state, but they both come to an almost skidding halt the moment they spot Sherlock, looking distinctly puzzled by their condition.

“Sherlock, what--” John sounds half-hysterical, torn between fury, amusement, and the receding edge of blind panic.

“ _Ah._ " Sherlock’s a bit embarrassed now, and he looks it, too, a warm flush slowly creeping into his cheeks. “There appears to have been a… misunderstanding.”

“Misundersta-- S _herlock, you didn’t bloody speak to either of us for two days!_ After you all but tucked tail and ran from our flat because we wanted to have a threesome with you! What the hell was I supposed to think, when you finally contacted me with some cryptic message that was the same thing, word-for-word, that you texted me during our first case together!”

Mary tries to shush her husband gently, though she looks only a little less unhappy than John. She places a hand gently over his arm and one on his back, giving Sherlock a look like she’s disappointed in him. It surprises him when it makes his stomach dip in something that’s almost humiliation. Sherlock, it seems, does not _like_ disappointing Mary.

“Sherlock, can you please just tell us what this is about? We’ve both been worried sick, and worried that we did something wrong…”

Sherlock’s almost frozen now, save for the heat in his face that he’s sure must have it at a proper shade of crimson.

“So then, ah… tea?” Sherlock manages at last, sounding a little meeker than usual. Mary glances toward John to make sure he’s not just ready to say _bugger it_ and storm off, before offering Sherlock a small smile and nod that’s an answer for both of them.

Clearly, he should have thought this through a little more before inviting them over.

* * * * * * * * * * * *

Once John’s got a good, strong cup of tea and a couple biscuits in him, he’s more-or-less calmed down. Obviously he’s still not thrilled with the way Sherlock’s gone about this, getting him all freaked out for nothing, but he’s rather used to this sort of treatment from Sherlock, anyway. Mary seems like she still can’t decide whether to be horribly amused by anything, or angry because of just how upset he managed to get John.

Sherlock’s at least smart enough to let them both appreciate the warm familiarity of a good cup of tea, though he’s barely touched his own. He even tops them both off with a fresh cup, before John finally cracks under the weight of the silence in the room.

“All right, are we _going_ to talk about this, or are you just going to keep stuffing me full of tea and biscuits all night?”

Sherlock’s confused, and maybe just a little hurt, but before he can answer, Mary cuts in. She’s really become quite the diplomatic go-between for the crime-solving duo.

“John, I know you’re upset, and he was a _bit_ of a prat, with the way he shut us out and all, but this is clearly a sort of touchy subject for Sherlock. Let’s just try to enjoy the fact that he’s actually made us tea,” and here Mary’s eyes twinkle with proper mischief, because she’s become quite familiar with how horrid a flatmate Sherlock had been, “and let him bring stuff up in his own time, all right?”

John finally agrees with a grumble and a world-weary sigh, and Sherlock gives Mary a look that’s rife with desperate gratitude, which she simply returns with a beatific smile. Luckily, her bit of reverse psychology, however intentional or not, has actually worked.

“I want to sleep with both of you,” Sherlock blurts after maybe ten seconds of additional silence. He’s never been very eloquent during _emotional_ conversations, but it’s thankfully something John’s pretty much grown used to.

“ _Okay_ ,” John responds slowly. “That’s something, at least.” Mary shushes him again, this time with a pinch to the side, drawing a sharp _ow_ and glare from her husband, which she ignores.

“It’s just that… I…” Sherlock’s squirming now, looking so deeply uncomfortable that Mary seems to be barely resisting the urge to move over to where he’s seated in his chair and give him a hug.

“I haven’t ever _had_ a threesome or anything, not really.” Sherlock’s finally found his tongue again, mostly by firmly addressing the ceiling. “And I’ve never been in bed with _either_ of you, and… Well, it would ease my concerns if I were able to watch you before I actually participate.”

Silence.

Sherlock tears his gaze away from the ceiling, glancing sharply toward John and Mary with scarcely-disguised panic in his eyes. _Has he said something wrong?_

But, no, he hasn’t ruined things _completely,_ it seems. Mary’s trying, and failing, to stifle her laughter behind a dainty hand, her shoulders shaking with mirth, and John’s staring at him like he can’t tell whether Sherlock’s serious or not.

“…Problem?” Sherlock sounds more defensive than he’d like, but he _feels_ defensive, like they’re having a laugh at his expense.

“Sherlock, did you just ask if you could watch us shag?”

“I need to get a proper grasp on your technique--”

This time, Mary bursts out into laughter aloud, and John joins in with a few incredulous chuckles. Sherlock’s face is dangerously hot, and he finally scowls and sets his cup loudly down on the table beside his chair, jumping to his feet.

“Fine, if you’re not _bloody_ interested, all you had to do was say--”

“Sherlock, we didn’t say we weren’t interested,” Mary begins, still smiling, though her expression’s starting to shift to one of concern.

“No, you just _laughed_ at me instead.” Sherlock’s trembling now, chest tight, eyes burning and vision blurring in a way that suggests he’s about to lose his composure completely and have some sort of meltdown right in front of them.

“Forget it. I’ll just delete it--”

_“Sherlock.”_ Sherlock stops abruptly at John’s voice. He stands in place, trying not to shake, while John carefully sets his own half-finished tea aside and rises, approaching him cautiously.

“We didn’t mean to have a laugh at you, either of us. It’s just the way you word things sometimes--” John seems to see something in Sherlock’s face that makes him stop, shaking his head. “It was just the way you went about it that tickled our fancy a bit. We’re both still _very_ interested. I promise.” John glances once to Mary for confirmation, then, and she nods. He licks his lips and continues.

“So, did you want to do this here, or at our flat?”


	4. Chapter 4

**Summary for the Chapter:**

> Sherlock observes.

After a minimal amount of discussion, and a little more giggling on the part of John and Mary that makes Sherlock scowl and flush anew, they finally decide that Sherlock’s bedroom is the best location. Though it’s sure to be rather awkward for the two of them initially, it will at least be more comfortable and familiar for Sherlock, who’s already displaying behaviour akin to a fish out of water.

“All right, Sherlock?” John asks, once they’re in the spacious, but cluttered room. They’ve closed and locked the door behind them to be safe, though they’ve done the same to the one Mrs. Hudson tends to enter without knocking.

Sherlock’s gone a bit shaky, heart fluttering anxiously against his ribcage, but he nods once. He’s already “tucked tail and ran” once, as John had put it, and now that he’s decided this is something he really wants, he has no intention of doing so a second time.

“Okay.” John still looks a little unsure of Sherlock’s desire to be here, but Mary shushes him with a soft brush of pink lips against his neck.

“Sherlock will let us know if he changes his mind, I’m sure.” Mary’s voice is quiet, but loud enough Sherlock can hear and give another nod. She smiles. “Would you like to have a seat, then? Not sure your bed would fit you and the both of us, and I just think that would be awkward, don’t you?”

As usual, Mary’s got an absolute gift for saying just the right thing in just the right way to set Sherlock at ease. It’s a talent she’s displayed with regards to her husband, as well.

“Yes, obviously.” Sherlock’s still clearly out of his depth, but he does look slightly calmer as he swiftly crosses the room to unceremoniously dump a pile of papers off his desk chair and onto the floor.

“Sorry, I-- erm, old case files. Haven’t gotten around to disposing of them yet.” Now Sherlock’s getting wound up about the state of his bedroom, hands fluttering as he tries to shove the discarded papers into some semblance of organisation.

“Sherlo--” John’s voice is all wrong to calm Sherlock anew,tinged with exasperation Mary knows Sherlock won’t appreciate in the slightest, so she quickly cuts him off.

“Sherlock, it’s okay. John and I hardly expected your room to pass a military inspection.” The last couple words end with a sly smile John’s way, a sort of light-hearted jab at his army background.

It works. Sherlock stops abruptly, inhaling deliberately before finally straightening and placing himself in the wooden chair he’s emptied.

“As you wish.”

John’s own expression and posture relax a little more, and he’s more than receptive to Mary sliding her hands along his stubbled jaw to bring his face toward hers for a long, slow kiss. It’s more thoughtful than passionate, though it hints at the possibility of more. When she pulls away some five or six seconds later, it’s to give him a warm, loving smile. Sherlock can’t help the small noise that escapes him, though it’s not exactly one of jealousy or other displeasure. Rather, he’s somehow intrigued, maybe even _pleased_ at the sight.

Odd.

“Why don’t we get you out of that shirt now, John? I’m sure Sherlock’s been wanting to get a good look at you for ages now.”

“Honestly, it’s not like there’s _that_ much to see.” John’s protests are half-hearted at best, especiallyas he doesn’t so much as try to move away as Mary’s deft fingers unfasten each of the buttons of his shirt, top to bottom.

“There, _that’s_ better.” Mary almost seems to have forgotten about Sherlock, though he suspects she’s simply making an effort to behave as naturally as possible while giving Sherlock a good bit of a show. She pushes John’s shirt off him with a noise that seems the feminine counterpart to the sound Sherlock had just made. Sherlock inhales abruptly when John’s torso is properly bared, the other parts of the respiratory process eluding him completely.

John is _magnificent._ Sherlock’s certain the average person would not think this of him, but the average person is an _idiot._ John’s age and relatively sedentary life has begun to show in a certain amount of growing pudge around the stomach and softening of the arms, but the lingering strength from his military service is still impossible to miss. There’s a fair sprinkling of hair on his chest and arms, leading in a trail that thickens and disappears into his jeans, mostly sandy but with a few hairs here and there that seem to be greying like the hair on his head.

The _scar,_ Sherlock thinks, is worthy of an entire room in his mind palace alone. It’s not beautiful by any standard definition of the word, but it’s _fascinating_ in its asymmetrical patterns of cordage in a way that matters much more to Sherlock than mere aesthetics.

Sherlock’s certain he’ll need to spend several hours exploring John’s scar later.

Mary has of course grown used to John’s scar. She doesn’t avoid it in the slightest, but seems to linger just a few seconds longer on it than the rest of him. Her fingers are almost as restless as Sherlock’s can be, roaming over rounded shoulders, wiry chest hair, and finally hardened nipples that appear to be surprisingly sensitive. Sherlock tucks the fact away for later use.

“Enjoying yourself?” John sounds amused, and he’s smiling at Mary, though he glances over to Sherlock as well, apparently directing the question to them both.

“So far, yes,” Sherlock answers, voice steady and certain. He steeples his fingers in front of his face, a clear indication to John that he’s both watching and absorbing.

“Don’t I always?” comes Mary’s reply, with another of her teasing smiles that Sherlock’s grown to enjoy. There’s something about her that almost lights up the room, to use a tired cliché.

“Well, much as _I_ am, too, I still think it’s only fair if _you_ lose your shirt, as well.” From the looks, and sound, of it, Mary brings John’s playful side out as well. “I’ll even be nice and let you keep your bra on, for now.”

“Now where would the fun in _that_ be?” Mary’s sly answer makes Sherlock’s pulse jump suddenly with nervousness. Generally speaking, he isn’t _into_ women, and he hasn’t entirely been able to pin down exactly how he feels about this one, or what his attraction to her is. But he did _ask_ to see the two of them in bed together before all three did anything, so he stays quiet and keeps his squirming to a minimum. John and Mary don’t seem to notice his moment of indecision, anyway.

Without further ado, Mary unfastens the buttons of her own shirt, bottom to top, and lets the pale blue garment fall. Her eyes lock onto John’s as she reaches behind herself, unhooking her white lace bra with only a little struggle. Clearly it’s one she wears frequently, Sherlock notes idly.

 And then the bra’s straps are sliding off her shoulders and the undergarment is joining the other discarded articles of clothing. Sherlock is… not _indifferent,_ that implies a certain apathy he doesn’t possess. Perhaps _ambivalence_ would be a better term for what he’s feeling right now. He isn’t sexually attracted to Mary in the traditional sense of the word, but neither is he repulsed by the sight of her partial nudity. In her own way, he thinks she’s even aesthetically pleasing.

Having apparently sorted _that_ part of his own feelings on their prospective arrangement out, Sherlock’s able to devote his full attention to the way John approaches his wife almost reverently, cupping one breast in his hand and lowering his head to draw her nipple into his mouth. Mary gasps her appreciation at that, and the faint twitch of Sherlock’s cock takes him by surprise.

“God, you’re gorgeous,” John growls in approval, and _now_ Sherlock’s not sure if his body’s reacting to the sight of John’s mouth attached to Mary’s right breast or the thought of John saying that to _him._ Either way, a tell-tale flush is working its way into his cheeks, and he’s on his way to a partial erection.

“Mmm, so you’ve told me,” Mary murmurs, eyes half-lidded with pleasure and what Sherlock can see of her eyes a darker blue than he’s noticed before -- the effects of arousal, no doubt.

John pulls away from her at last, licking his lips and skimming his gaze shamelessly from her face down to her semi-nude body and back up again.

“What do you say we both get out of the rest of this clothing, then?” Mary smiles at his question, glancing almost lazily over to where Sherlock’s fidgeting in his seat now, fingers wrestles where they’ve wrapped around the arms of his worn wooden chair. Though he’s not hard enough yet for _that_ to be visible, he’s sure they can both read his arousal, all the same.

“So long as Sherlock’s all right with it,” Mary answers, eyes only on Sherlock now.

Sherlock’s not sure he’s ever been _more_ all right with anything in his life.

 


	5. Chapter 5

**Summary for the Chapter:**

> Things get particularly heated.

A few awkward minutes shuffle by, as John and Mary get occasionally tangled up in clothing and go for the same button at the same time. There’s something so carefree about the way they behave in the bedroom, the same way they act outside of it. This whole event is thus far standing in stark contrast to all of Sherlock’s previous sexual experiences.

At last, John’s down to his nondescript, greyish pants and Mary’s swatting his hands away so she can divest herself of her own trousers. The two full minutes they’ve taken to get to this point have actually served to ease what was left of Sherlock’s anxiety. In its wake, Sherlock’s arousal is slowly swelling.

“I think Sherlock’s enjoying himself, hm?” Mary’s hushed voice is conspiratorial, though the grin she throws Sherlock’s way makes it clear she knows he can hear him. Sherlock fights not to smile, though it’s a losing battle. At the moment, he’s also fighting not to adjust himself in his trousers while either of them is looking at him. Silly, but he’s loath to admit how much he _is_ enjoying this.

“He’s not the only one,” John replies, hands sliding around to Mary’s bum in a way that suggests he does this a lot, and Mary squeals a little as he abruptly pulls her in closer. John’s visible erection, still covered, presses against Mary’s stomach as he pulls her against him for a long, rather filthy kiss. Then it’s Mary’s turn to be devious, sliding a hand down to grasp John’s erection while he’s distracted by kissing her. He gasps, and Sherlock inhales shakily at the sound.

“Sneaky sneaky,” John murmurs, voice low and growly with arousal as Mary locks eyes with him cheekily, stroking him through his underwear until a small damp patch forms at the head of his cock.

“You _like_ it,” Mary responds. Pushing John gentlybut firmly onto his back until he falls back on the bed, Mary wriggles her way down to slide John’s last garment off and leave it somewhere near the foot of the bed.

Sherlock very nearly lets out a noise that he’s sure would have been _pathetically_ needy, because now John’s cock is completely exposed to him, if only to devour with his eyes. John’s of about average size, maybe a centimetre or two over, though it’s hard to tell without getting a closer look. He’s pleasantly thick, too, curved just a little toward his bellybutton and off to the left, and his foreskin is loose enough that his glistening, ruddy head is exposed.

John’s cock, Sherlock immediately decides, looks positively _mouthwatering._

Apparently Mary’s line of thought is similar to Sherlock’s, because her head soon ducks down so that she can draw her tongue from the base of John’s cock up toward the tip. John swears, hips twitching automatically, though he tangles his fingers in the sheets for now. _Interesting._ It appears Mary takes charge in the bedroom, at least to an extent and on some occasions. Sherlock is somewhat surprised to find he wants additional data on this.

“Easy, love,” Mary murmurs, even as she drags the tip of her tongue over, presumably, the very tip of John’s cock, making him actually _whine._ Finally, she seems to take pity on him. One slender hand grasps the base of John’s cock, holding him in place as she wraps her lips around him.

John’s head falls onto the pillow, eyes fluttering closed as he just lies back and enjoys Mary’s apparent expertise. Sherlock’s sucked a fair amount of cock himself, so he can appreciate that this is far from Mary’s first time. She’s liberal with her saliva, ensuring John’s entire shaft is slick for the movements of both her lips and fist, which rarely stay still for long. Periodically, Mary slows her tempo down, withdrawing almost completely to the head of John’s cock to swirl her tongue around it in a way that makes John groan from somewhere deep in his chest.

Maybe thirty seconds into the blowjob, and Sherlock’s given up all pretences that this isn’t arousing as hell to him. With a frustrated noise that miraculously goes unnoticed, he yanks his trousers open and pulls his cock out. The relief of pressure against his sensitive flesh is immediate, and he sighs softly, simply enjoying it for two or three seconds. He doesn’t even realise, at first, that Mary’s glanced over to him again until he lifts his gaze back to the bed.

Mary’s stopped sucking John almost completely, and John’s finally lifted his head and opened his eyes to see why. The result of this, of course, is that _both_ of them are now staring at Sherlock, who flushes and immediately moves to cover himself.

“No. Don’t.” John’s voice is soft, not so much an order as a gentle request, and Sherlock cautiously uncovers himself.

“You’ve been holding out on us,” Mary murmurs appreciatively, and Sherlock’s sure now that his face, neck, and ears are all burning red. He knows he’s got a fairly nice-looking cock, as far as they go, but he’s never been complimented _quite_ like that before.

“You just planning on staring at him all day?” John’s hips move pointedly, making his cock bob almost comically against his stomach, and Mary smirks as she finally pullsher gaze away from Sherlock. John seems to have a harder time of it, but apparently he’s willing to wait until they progress into things further. His fingers run through Mary’s hair a little, which has begun to come undone, and she tilts her head in consideration as her fist idly pumps his prick.

“I dunno, I think it’s just about my turn, don’t you?” The smile Mary flashes at her husband is so full of wicked mischief that John can’t help but smirk, shaking his head hopelessly. She really does have him wrapped around her little finger, in at least a few ways.

“Why don’t you pull those knickers off and come on up here, then?” John pats his chest, as if his meaning wasn’t clear enough, and Mary’s quick to pull her underwear off and climb up John’s body to straddle his face.

Sherlock can’t tell _exactly_ what John’s doing, and hasn’t decided for sure yet whether he’d like to know, but it’s clear John’s got some serious experience in the art of cunnilingus, as he draws a small sigh of appreciation from Mary almost immediately. Sherlock’s erection hasn’t subsided in the slightest and is giving a rather insistent throb at this point, so he finally reluctantly slicks his palm with his tongue to wrap his fingers around himself.

While John rather leisurely eats his wife out, Sherlock strokes his cock in much the same fashion. He’s in no hurry to get off, particularly as the pair in bed seem to be just getting started, he just needs to give his cock _some_ amount of attention before it gets outright painful.

John’s hands grip Mary’s arse as he enthusiastically pleasures her, and Sherlock finds his breathing growing heavier as Mary’s gasps and moans increase with the undulations of her hips. There’s a moment when John has to pull back to catch his breath properly, and Sherlock pulls his hand away from his cock completely.

For the time being, John and Mary seem to have almost forgotten about him, and Sherlock’s just fine with that. He almost feels like he’s intruding, with the way Mary lovingly runs her fingers through John’s greying hair and murmurs filthy comments about how _ridiculously_ good he is at this.

At last, John nods and Mary moves from her position on his chest to back over his face. He seems to be working her back up to where they were, and Sherlock matches their pace almost unconsciously. Mary’s gripping the headboard a half-minute later as she rides John’s face, and it seems no time at all before she stiffens, then lets out a sound halfway between a groan and a cry, her body shuddering as John no doubt coaxes her through her orgasm.

Sherlock has to take his hand off his cock abruptly lest he fall over the edge with Mary. Cock throbbing angrily at the sudden lack of stimulation, he watches Mary slowly still, then finally lift up and wriggle down a bit so John can breathe again.

“God I love you,” Mary murmurs, and Sherlock would bet money that John’s smirking in self-satisfaction right now. Finally, she turns around to glance at Sherlock, giving a deliberate glance down toward his groin again.

“Think we’re about ready to get to the ‘main event,’ so to speak. As long as neither of my boys has any problem with that.”

The warmth which unfolds in Sherlock’s chest almost manages to eclipse his arousal.


	6. Chapter 6

**Summary for the Chapter:**

> A finale.

**Notes for the Chapter:**

> I'm sorry this one took so long! I've no intention of abandoning this fic anytime soon. Het smut is just really awkward for me to write, apparently??

Though Sherlock’s not sure that his role in this event is strictly one of a bystander any longer, he remains in his chair as John and Mary arrange themselves more comfortably. Mary lies on her side, facing away from Sherlock, and John soon slides behind her. His mouth moves along her neck, drawing soft sighs of appreciation, while Sherlock simply watches them quietly.

John eases Mary’s leg up slightly, enough that he’ll be able to tell what he’s doing better, and then he slides into her. When John groans softly, Sherlock shudders, his cock throbbing in sympathy. He finds he can’t hold off on stroking himself any longer, and finally he returns his hand to his erection to squeeze it slightly.

For all their long build-up, John and Mary don’t seem to be in any particular hurry to end things now. Even after John’s slid fully into her, he just stays there and enjoys the sensation, his left hand running up Mary’s side. Sherlock can’t see exactly what he’s doing, but it clearly involves Mary’s breast, and she clearly enjoys it. John’s lips seem to be moving against her neck, as well. _Sensitive, apparently._ Sherlock makes a note of that.

When John finally begins to thrust, his hips move languidly, unhurriedly. Mary hardly seems to mind, considering her recent orgasm. Her head twists around toward John, just visible from Sherlock’s angle, and she kisses her husband as slowly and deeply as she can manage, given the awkward positioning. After perhaps a minute or two longer, though, John’s ready to change positions, and Mary appears to agree.

“Preference for who’s on top?” John murmurs, and Mary chuckles in response.

“I’ve already been on top of you once tonight and don’t much fancy doing all the work for this.” This time John laughs, though he nods, accepting her decision. Withdrawing, John lets Mary arrange herself on her back, legs spread rather shamelessly.

“God, you’re beautiful.”

Sherlock’s face flushes, and he momentarily averts his eyes. He suddenly feels like he’s stumbled upon something too intimate for his presence and wonders if this was a good idea at all. But the view he has of John right now, nude with erect cock bobbing lewdly out in front of his body, almost manages to erase his fears.

Ever the doctor, John glances over to Sherlock, making an apologetic face.

“Do you happen to have any condoms, Sherlock? Didn’t exactly bring any with me.”

“Bedside table.” Sherlock’s voice actually sounds reasonably composed, and he’s grateful now that he picked up a box when he was still feeling hopeful about his future with John. Of course, he hadn’t imagined that future would involve John’s new wife, as well.

“Thank God,” John breathes, reaching over to fumble the bedside table drawer open and pulling out one of a fair handful of condoms within. The small bottle of lube that’s in there, too, won’t be necessary, not with how wet Mary is right now.

“Any day now would be lovely,” Mary comments, though she doesn’t sound truly impatient or irritable. Besides, her legs are falling open just a bit wider now, making John hurry to tear open the condom wrapper and roll the latex barrier down over his cock.

Finally, John positions himself between his wife’s thighs, sliding a hand down to grip himself and tease Mary a bit. She gasps, back arching, and John grins wickedly before finally guiding himself into her. They sigh in pleasured almost-unison as he slides in all the way to the hilt, and Sherlock bites down hard on his lower lip as he reluctantly slides his hand back down to his erection once more.

John’s as unhurried as he’s been thus far, stretching up to give Mary a long, slow, deep kiss while he grinds his hips into hers. She lets out a small noise of pleasure into his mouth, and her hands slide down to grasp his arse and pull him harder into her.

“Impatient, aren’t we?” John murmurs, chuckling breathily. But he does finally shift his weight so he can support himself, pulling out of Mary most of the way before sinking back into her. He’s soon establishing a rhythm of slow, deep thrusting that makes Sherlock ache with the urge to be in Mary’s position.

Sherlock can hardly hold still in his seat as he watches John fuck Mary in his leisurely way. He’s embarrassed to realise how much he’s itching to wet a couple fingers and slide them down and into himself. For now, he suppresses the urge, rolling his thumb over the head of his cock in a way that’s almost painfully pleasurable. His eyes are dark, fixed on the movements of John’s hips as his cock moves in and out of Mary, and his breathing’s shallow.

“Fuck,” Mary gasps, digging manicured nails into John’s arse cheeks and making him grunt in a way that doesn’t sound too unhappy with the pain. “Harder.”

John grins at the request – or command, really – but seems happy to oblige. All it takes is a small shift in position to give him better leverage before he starts fucking her with real enthusiasm. It isn’t long before the moist smack of skin against skin is mixing with pants, moans, and the overwhelming smell of _sex._

Sherlock groans a curse under his breath that echoes Mary, fist pumping more desperately over his cock. Already, he can feel the tightening coil in his groin, the slow build of pressure somewhere in his testicles as he nears his orgasm. He clenches down on the muscles there, gritting his teeth as he holds it stubbornly at bay.

Luckily for Sherlock, John and Mary are at nearly the same point as he. John’s swearing colourfully under his breath, and Mary’s slid a hand down between her legs to rub frantic circles into her clit. It can’t be more than ten seconds later that Mary’s back arches, her whole body shuddering as she lets out a guttural cry of pleasure. She’s no doubt clenching and convulsing around John, so it takes only another couple thrusts before he buries himself in her, gasping and swearing again as his hips jerk.

The sounds, smells, visual of it all provide more than enough of a push to tip Sherlock into his own orgasm. When it hits, Sherlock nearly forgets how to breathe. His hips jerk, sending thick shots of semen high up onto his chest, and he finally lets out a deep groan as he finishes stroking himself through climax, until he’s wrung the last few drops of cum from his prick.

“Jesus, Sherlock,” John gasps. He’s still inside Mary, just staring at Sherlock, and grinning tiredly. “Trying to outdo me?”

Mary’s giggling almost soundlessly, her whole body shaking with it even as John carefully holds the condom in place around his softening cock to pull out of her. He pulls the condom off and ties the end with practised ease, lobbing it at Sherlock’s already overflowing rubbish bin with remarkable accuracy.

Now that he’s gotten off, Sherlock’s quickly losing the last of his arousal to embarrassment.

“I don’t-- I didn’t--” Sherlock stumbles over his words, tongue damnably clumsy. Mary, angel that she is, saves him from further humiliation.

“Sherlock, love, it’s fine. We’re both _very_ happy that you enjoyed yourself so much, aren’t we, John?” Mary nudges her husband with a knee, and he nods decisively. Sherlock finally relaxes a little, though his face is still hot.

“Could use a bit of a clean-up now, though,” John continues rather conversationally, grinning at his friend. “Don’t think all three of us will fit in the shower, unfortunately, so I suppose we should just take turns.”

Sherlock can only nod. His head’s still all fuzzy with the aftermath of an earth-shattering orgasm, and he hasn’t decided yet if he _likes_ the feeling or not. At least it keeps him from falling back into the panic that would probably be settling in, otherwise, over where the three of them are going to go next.

 


	7. Chapter 7

**Summary for the Chapter:**

> Sherlock and Mary come to more of an accord.

Of course, the day after their first sexual encounter, Lestrade phones with a case. Sherlock gleefully enlists not only John’s help, but Mary’s as well, and as a result he has it solved in record time. John’s wrong assumptions are perfect for helping Sherlock pinpoint the right deductions, and Mary provides a few key comments that have the suspect under custody within three hours.

When they get back to 221B, all three of them are animatedly discussing the case, laughing. Sherlock’s actually _giggling._ They lean against the wall just inside the main door, and the whole scene’s reminiscent of his and John’s first case together so very long ago.

Sherlock’s surprised to find there’s nothing painful in remembering that or noting the similarities. Things are different now, yes, but they’re not really _worse._

“Fancy a bit of takeaway?” John asks, once they’ve gotten their giggling, and breath, under control. “I’m _starved.”_

Sherlock is tempted to make some flippant comment about how _boring_ eating is, but Mary chimes in with an enthusiastic suggestion for dim sum. It’s another similarity, and it whittles his remaining resolve down to nil.

“I suppose I could choke a few mouthfuls down,” Sherlock responds airily. Apparently his attempts at being aloof and above human necessity fail, though, because he catches John and Mary giving each other a tiny little smile. More of their _married_ telepathy, or whatever rubbish it is.

In the end, John volunteers to go fetch the food, since it’s not more than a couple streets away, and he’s still clearly riding his adrenaline high, and Mary gives him a kiss. John glances to Sherlock like he’s half-expecting the same from him, but Sherlock can only stare. _Is that what they are now? A couple? The sort who give each other casual kisses?_

Luckily, John doesn’t seem too offended or hurt, so much as a little disappointed, and it’s soon just Sherlock and Mary in the landing.

“After you,” Sherlock murmurs, gesturing gallantly for Mary to precede him up the stairs to the flat.

“Such a gentleman,” Mary replies with her trademark saucy smile, though she climbs the stairs as indicated.

“I’d, erm, offer you a drink, but I don’t think I’ve much in, unless Mrs. Hudson’s been secretly stocking my pantries again,” Sherlock calls out over his shoulder as he divests himself of his coat and scarf to hang them up. Mary’s already seated herself on the sofa and is ridding herself of the same, which Sherlock holds out a hand to take. This time, she looks genuinely surprised.

“And here John had me thinking you were all wrapped up in yourself all the time.” Sherlock flushes, though Mary delivers the comment gently enough that he doesn’t outright bristle. Nevertheless, he’s silent as he crosses the room to hang up her coat and scarf.

So! Married life with John seems to be suiting you nicely,” Sherlock throws out. He’s started pacing almost without realising it, too anxious to sit still. When he glances Mary’s way, her face has softened. _Is he that bloody transparent?_

“Sherlock, you don’t have to try to make small talk with me. I don’t mind a little silence now and then, and I think it’s a testament to one’s relationship when you can sit in comfortable silence together.” Mary’s eyes are warm and considering as they rest on his. “You and John are like that, aren’t you?”

Sherlock comes to an abrupt halt, staring at Mary before tearing his gaze away to flick aimlessly about the flat. He deduces quite by habit, picking up on the details of Mrs. Hudson’s recent presence -- and Mycroft’s, he’s less pleased to note. _She’s jealous, she’s afraid of our relationship. She’s afraid John will choose me over her._

As if she can read his thoughts, Mary slides forward until her weight’s resting on the very edge of the sofa. Sherlock’s eyes flick swiftly back toward her automatically, and he sees she’s… _understanding?_ That’s a way of putting it, anyway.

“I’m not jealous,” Sherlock blurts abruptly, absurdly. Mary at least does him the justice of not laughing at him, or even smiling too much.

“I didn’t think you were,” Mary responds softly. “Well, not as such. Though I could tell you were regretting never acting on your feelings for John. It’s part of why I kept prodding him to make up with you. I knew he felt the same way about you.”

Mary Watson, née Morstan, has struck Sherlock speechless.

“Oh.” Sherlock doesn’t so much murmur his response as breathe it, in the same sort of tone reserved for sudden revelations in mid-case. “ _Oh._ ”

“Yeah,” Mary responds, smiling in such a way that it comes across even through her tone.

Sherlock could kiss her.

Thankfully, or unfortunately, the front door opens and slams a moment later, making Sherlock jump almost guiltily. A part of him is certain John would _enjoy_ watching Sherlock kiss Mary, but he’s still not sure exactly what his feelings toward her are. They’re positive, certainly, but beyond that? Well, women really _haven’t_ been his area.

Sherlock? Mary?” John’s calling out as he trudges up the stairs, and oh how Sherlock’s missed the sound of his tread.

“In here, love,” Mary answers for them. Sherlock swiftly throws himself into his armchair and steeples his fingers, some attempt at hiding the conversation they’ve just had.

“Glad to see you two are still in one piece,” John throws out with a smile, carrying two hefty paper bags straight over to the kitchen table. He _tsks_ at the mess he finds there, since Sherlock’s converted it almost entirely into a makeshift laboratory now that the flat is all his, but he’s humming quietly as he methodically disposes of Sherlock’s experiments.

For once, Sherlock doesn’t much mind.

 

 

 


	8. Chapter 8

**Summary for the Chapter:**

> A respite of sorts.

Through some unspoken accord (perhaps this _telepathy_ thing isn’t just for John and Mary after all), all three of them don’t take a single step toward the bedroom again for nearly a week. Instead, they settle into some strange new form of domesticity. Sherlock is still living at 221B, alone, but John and Mary visit and stay over two days in a row. Thankfully, John’s old room still at least contains a bed large enough for the married couple.

The two days John and Mary are at 221B pass by in fairly blissful indolence. Sherlock’s just finished a case with both of their help so his mind isn’t quite tearing itself to pieces again yet. He still takes up the entire sofa and demands John makes him tea, though Mary eventually steps in and tells him he can make his own bloody tea. John sits in his armchair and Mary sits in Sherlock’s, and the three of them mostly read newspapers and books separately, or work on John’s blog (partly in collaboration with Mary, now), or actually sit on the sofa together to watch a film on the telly.

Sherlock’s never much cared for the vast majority of films, but he lets John and Mary bicker over which one to watch. Naturally, Mary wins, and Sherlock’s grateful for it. He deletes the name of the film five minutes in, but it’s interesting enough that he isn’t completely bored out of his mind, and Mary only has to hiss at him to stop texting some five or six times.

Perhaps the claim that he’s not completely bored with the film is a lie after all, because Sherlock winds up dozing a little over halfway through. He ends up curled with his head on John’s shoulder, his feet tucked comfortably against Mary’s thigh. Though he isn’t aware of it, both of them make more than a few comments about the way he snuffles and mumbles half-lucid deductions in his sleep. Really, they both seem fairly infatuated with him, though in different ways.

By the time the credits are rolling, Sherlock’s ended up on his side in a way that’d surely leave him sore if he stayed that way too long. His head is in John’s lap, his feet in Mary’s, and Mary is trying her damnedest to stifle her laughs so she won’t wake him.

In the end, it’s John who wakes Sherlock by slowly running his fingers through his hair and murmuring silly things about how it’s time for sleepy geniuses to get up and go to bed. Sherlock’s half-sleeping grumble is that they should come to bed with him.

“Sorry, love, don’t think your bed’s nearly large enough for three,” Mary responds quietly, though Sherlock just grunts in a way that means he’s probably not absorbing a word she says.

“Come on, now. Up with you, and if you’re good, we’ll both tuck you in.” John’s promise sounds absurd, even childish, but it’s enough to get Sherlock to stir and groggily lurch to his feet.

“Hey, hey, this way.” John’s up on his feet a half-second after Sherlock, sliding an arm around his waist to guide him to his bedroom. Sherlock leans into him contentedly and murmurs something about John smelling like home. Honestly, the man sounds almost drunk when he’s half-asleep.

“Mary?” Sherlock slurs as John eases him into bed. He lifts himself up halfway, then falls heavily onto his back again when her familiar outline enters the room.

“Easy, dear. I’m right here, and you need to sleep.” Sherlock makes a noise that sounds like he agrees, and John makes good on his promise to tuck Sherlock in, though he feels a little silly doing so.

“Sleep tight,” Mary whispers, though Sherlock’s already beginning to doze again. He’s only vaguely aware of warm lips on his forehead before he’s drifting.

 * * * * * * * * * * * *

In the morning, Sherlock wakes to an empty flat. He can _sense_ it, absurd as it sounds, and he just barely resists the urge to fire off a frantic text to John. They don’t live at 221B, he knows that, but he can’t believe they left without saying goodbye.

Eventually, Sherlock finds the energy to drag himself off to shower, trudging half-dressed and in his dressing gown off to the kitchen for tea shortly after. It’s only then that he finds the note, penned in Mary’s slightly clumsy cursive.

_I’m sorry we couldn’t stay long enough to see him up and eating breakfast, for once, but John and I both have to be back to work, and we needed to pop in at home for our things. Try to eat a little something, at least. There’s a can of beans by the toaster, and the bread looks all right still. We’ll see you later, love._

_Mary xo_

Staring at the scrap of paper and the silly little hug and kiss at the end, Sherlock can almost imagine Mary going to mark the _x_ and _o_ and John telling her she was being ridiculous, that Sherlock didn’t go in for that sort of sentimental rubbish. She would have ignored him, of course, and the proof of it is sitting right in front of him.

Sherlock smiles, a hand sliding into his dressing gown pocket to retrieve his mobile. The text he sends is short and to the point, and he sends it to both John and Mary.

  _Thank you. SH_

* * * * * * * * * * * *

The day Mary and John depart for a bit, after leaving that note for him, Sherlock finds himself more content than he’s been in ages. It’s been months, maybe even years, since he’s felt this much at ease, though the crushing misery of _that_ possibility convinces Sherlock not to think into it too hard.

Instead, Sherlock buries himself in his experiments. John’s absence from the flat (for the most part, at least) has allowed Sherlock to store much larger quantities of body parts and other useful materials in the refrigerator and kitchen at large. He conducts studies of mold, mildew, and fungus on much larger scales than he could have before-- _before._

Mrs. Hudson pops in twice during the day with a cheerful greeting, and Sherlock actually smiles at her and tolerates her mindless chatter about Mrs. Turner and her married ones (he’s surprised they’re still living in the same flat, and still married, after all this time). In the end, he’s so _different_ from the way he’s normally behaved that she actually stops and comments on it.

“Sherlock, have you found yourself a new man?” Mrs. Hudson knows of his tendency toward the male gender, she always has, though he’s never bothered to explain the complexities of his _sexuality,_ or general lack thereof.

“What? No, _no_ ,” Sherlock responds, though something about his tone, or how hastily he answers her, makes Mrs. Hudson consider him thoughtfully. She’s cleverer than most people give her credit for, even Sherlock.

“Well, I suppose you always were going to be a part of John’s life, marriage or not,” Mrs. Hudson finally sighs, gathering up the detritus from Sherlock’s half-finished lunch (he’d been in the middle of an _important_ experiment) and shuffling over to the sink to wash up the dishes. “Still, I hope you know what you’re getting yourself into. Those three-way relationships can get dreadfully complicated.”

It’s quite possibly the first time Mrs. Hudson has managed to render Sherlock completely speechless. 

 

 

 


	9. Chapter 9

**Summary for the Chapter:**

> Domestic bliss and the bedroom.

**Notes for the Chapter:**

> I'm really sorry my chapter production has slowed way down. My mental health has been horrible again lately, and I haven't really been sleeping, either. Still don't plan on abandoning this fic anytime soon, just bear with me for the slowness!

“Don’t even think about dragging any of your flasks and beakers over here, just because we’ve had you over a couple days now,” Mary instructs, brandishing her wooden spoon at Sherlock.

“God, _please_ no,” John tacks on, shuffling around his wife to turn the stovetop on for her. “I definitely don’t miss having to dodge body parts to find edible food in the kitchen.”

“I don’t see why you’re both so convinced I’m going to convert your kitchen into a laboratory,” Sherlock sniffs. “I already have a perfectly acceptable lab back at Baker Street.”

“ _Sherlock._ ” Mary’s quickly perfected the tone of voice that actually gets him to listen to her, most of the time.

“Yes, yes, all right. No experiments in your kitchen.”

“ _Or_ the rest of the flat,” John tacks on, turning to give a pointed stare to Sherlock, who’s seated at the kitchen table with John’s laptop open in front of him in a pointless attempting at finding a new case. After all, it’s been nearly a week again, and he’s starting to get restless.

“John, you can’t honestly expect me to abide by your silly little rule, when I could need to run an experiment that could save a person’s--”

“ _Not in our flat_ ,” John repeats more firmly. This time John’s giving Sherlock his sternest look, making him scowl and sink deeper down into his wooden chair in a strop.

“ _Fine_ ,” Sherlock grumbles. Mary casts a glance over at him and barely manages to hide her smile at his expression before she turns back to her meal preparations.

“Thank you. Now if you’re quite done pouting, I could use a bit of help marinating the fish for tonight.”

 * * * * * * * * * * * *

Perhaps it’s no real surprise that a good, home-cooked meal is enough to rekindle the slow simmer of tension-slash-possibility that exists when the three of them are alone together.

After they’ve finished eating, Sherlock somehow ends up on the sofa between John and Mary. They’ve turned on some crap telly, though none of them are paying too much attention. And finally, Sherlock can’t resist the urge any longer.

Shifting closer to John, Sherlock slides a hand up to his jaw and uses the gentle hold to pull him into a kiss. Something like relief makes John relax against him before he returns the kiss with clear enthusiasm. What starts off somewhat tentative soon becomes a proper heated snog, and the two men nearly forget about Mary’s presence completely.

When they break for air a full couple minutes later, John quirks his lips in a crooked sort of smile over Sherlock’s shoulder at his wife.  Sherlock cranes his neck around to see Mary’s looking terribly amused and nearly as aroused as he is. John’s response is, of course, to run his fingers through Sherlock’s dark hair and anchor them in his curls.

“I think it’s about time we take this to the bedroom, hm?” It’s definitely a question, for which Sherlock is immensely grateful, but he quickly nods his assent.

“If you weren’t so bloody big and gangly, I’d be tempted to carry you,” John tacks on with a smirk, and Sherlock scowls. It isn’t _his_ fault John’s so short.

Sensing he’s annoyed Sherlock, John makes amends by giving him another warm kiss. When he pulls away, it’s to forego his grasp of Sherlock’s hair in favour of taking hold of his hand instead. Sherlock’s more than happy to let John pull him firmly from the sofa.

John seems comfortable and sure of himself in a way that puts Sherlock more at ease about this whole situation and this new step they’re taking together. It _has_ been a while, but he can think of no one with whom he would rather ease back into sex.

* * * * * * * * * * * *

“Why don’t you two get started, hm? I think it’s about time Sherlock got a little action of his own, and I certainly don’t mind watching.” What seems a generous offer from Mary is, no doubt, an opportunity to tease herself while she watches her husband have his way with another man. Luckily, neither John nor Sherlock much minds.

“God, do you have any idea how long I’ve been waiting to get you undressed?” John breathes, steadily pushing Sherlock back toward the bed while his fingers work at the buttons on Sherlock’s shirt. Sherlock is breathing too heavily and feeling a bit too… anxious -- no, _nervous,_ there’s a clear distinction in his mind -- to be much help. He swallows once, glancing over automatically to Mary. She’s already stripped down to just her t-shirt and knickers and is running her hands over herself in an unhurried fashion, groping her breasts and sliding a hand down between her thighs.

Sherlock breathes in again, sharply, and turns his attention back to John.

“All right?” John’s paused in the act of unbuttoning Sherlock’s shirt, brow creased with worry, and Sherlock very nearly gives into the impulse to press his lips right _there_ at that particular wrinkle between John’s eyebrows. A half-second later, he realises he hasn’t actually replied, and that John appears on the verge of pulling away completely.

“Yes, I-- I'm fine. Really. John.” Sherlock starts out stammering, but he manages to slow his speech with a well-placed breath. He finishes up with his tone convincing enough that John smiles, and Sherlock smiles back.

“It’s only been a while, and everything’s…”

“Overwhelming?” John’s always understood the way Sherlock’s mind operates, better than any other _normal_ person, and Sherlock’s unbelievably grateful for it in that instant.

“Yes,” Sherlock responds carefully, before he very deliberately winds his arms around John’s neck. Mary’s smiling, he can just see in the corner of his eye, though for the moment at least it’s just him and John. _Just the two of them against the rest of the world._

There’s a word on the tip of Sherlock’s tongue, just then, that word he never dreamed he’d utter again properly. _Love._ Sherlock forces it back down with effort. Now’s not the time, not when they’ve only just tumbled into bed together, and a part of him can’t help but want the moment to take place sometime when Mary’s not present. Sherlock doesn’t mind sharing John, truly, but he _needs_ that moment to be his and John’s alone, as he imagines John and Mary need their own moments and intervals away from him.

“Thank you,” Sherlock murmurs at last, when John’s begun shifting uncomfortably under the weight of his stare. It isn’t quite what Sherlock had been longing to say, but it will suffice for now, and it still makes John’s expression go _tender_ in a way that aches like an overdose of sweets.

But then, John’s always had an unusual effect on him. 


	10. Chapter 10

**Summary for the Chapter:**

> John undresses Sherlock, but Mary's next.

**Notes for the Chapter:**

> I am so sorry this took so so long to finish, but here's a good 1.1k of smut for you, for those of you who are even still following this silly little thing. I did start on a parentlock fic that's a loose sequel to this one, too. I'm planning on uploading it sometime after I finish this one. I'm a good ways into the first chapter atm, so we'll see how that goes.

Sherlock lets John undress him most of the way, if only because John seems almost awestruck by every new area of bare flesh revealed. John’s lips and fingers pay homage to Sherlock’s body, revealing secondary erogenous zones Sherlock hadn’t even known he possessed.

“Fuck, John,” Sherlock gasps, when John gives an experimental pinch to Sherlock’s let nipple. Looking far too pleased with himself, John decides to attack the other nipple with his mouth. This time, Sherlock’s knees almost buckle, and John chuckles roughly as he steadies him with an arm around his waist.

“Easy, love.” Though Sherlock’s never much cared for pet names, there’s something  _right_  about hearing them from John’s lips. A softer chuckle sounds from the other side of the room, and Sherlock glances sharply toward Mary.

“Am I going to have to worry about the two of you nudging me right out of this relationship?” Mary’s tone is light and teasing, but Sherlock’s sure there’s a hint of real anxiety there. His mouth opens to try to reassure her, but  _reassurances_  really aren’t his area. It’s John who saves the day.

“Don’t think you’re getting off  _that_  easy, Mrs. Watson,” John replies with a grin. “Soon as I get Sherlock all hot and bothered, I’m coming for  _you_.”

There’s a moment where Sherlock’s certain he should still chime in with something witty, but words continue to absolutely evade him. He settles for a wink at Mary, before pulling John in for a kiss. It’s much easier to focus on the taste and texture of John’s lips and tongue, categorising everything for the John Watson room in his mind palace.

Though he lets out a breathy sort of laugh against Sherlock’s lips at the enthusiasm, John doesn’t complain. He’s a clever man, at least in this aspect, and even as he kisses Sherlock he’s pressing him back onto the bed so he can straddle him. When John finally pulls away, it’s to gaze at him with eyes grown much darker with arousal.

“You can touch me, you know. You’ve got my full permission.” John’s lips quirk, and Sherlock scowls automatically. He dislikes being made to feel  _stupid._

“I know  _that_ ,” Sherlock snaps, and he’s pretty sure he can hear stifled laughter from Mary’s side of the room. He ignores it in favour of sliding his hands tentatively up John’s thighs (padded with the softness of sedentary life, but there’s still a hint of muscle beneath) and experimentally around to his arse.

“ _Much_  better.” John’s voice has a growling quality now that’s more arousing than it should be, and Sherlock nearly trembles under the look John’s giving him. Before that stare becomes too much, though, John ducks his head down to assault Sherlock’s neck. The throaty groan that leaves Sherlock surprises even him, and his hips lift automatically in a bid for friction. He’s not disappointed, the heat and weight of John’s own arousal brushing against him.

“Like that, do you?” John murmurs, the very tip of his tongue dragging along Sherlock’s throat in a way that makes him positively  _shudder_. When he  _bites_  down, Sherlock lets out a noise that’s not only obscene, but  _embarrassingly_  loud, and John pulls away with a look of smug satisfaction on his face.

“About time.” Mary’s voice is nothing but playfully teasing as she winds her arms around John’s neck and presses herself close for a long, heated kiss. By the end of it, John’s hands have slid around to Mary’s arse, kneading even as he uses his grip to grind into her. When she pulls away, it’s only to arch a brow up at him, the angle of her head and quirk of her lips positively cheeky.

“You’re far overdressed for the occasion,” Mary remarks in answer to John’s questioning expression, and he lets out a soft chuckle as he pulls back enough to obey the implicit request.

Sherlock’s attention is positively riveted to John as his roommate-turned-friend-turned-lover begins to undress. John Watson is not handsome in the conventional way, and he’s neither military fit nor even as toned as he once was, but that makes him no less  _perfect_  in Sherlock’s eyes--and probably in Mary’s, as well. Breathing shallowly, Sherlock slides a hand slowly downward to tease himself.

“Like what you see?” John’s bemused question is directed at Mary, but he could just as easily be talking to Sherlock, who  _definitely_  does appreciate the view. Mary simply lets out a noise of mock annoyance at John’s excessive self-assurance.

“Keep that up and I’ll go on another blowjob strike, though I imagine Sherlock wouldn’t mind picking up the slack in that case.” A sly glance Sherlock’s way catches him flushing, resisting the urge to squirm. He enjoys the thought of fellating John more than he’d like to admit. God, this is all terrifyingly new.

“Mm, if you’re going to talk like  _that_ , someone’ll need to suck me.” When Mary gives her husband a pointed look, he sighs, though the way he curls his arms around her waist is still tender.

“You know I’ve no problem with returning the favour.” While Sherlock knows there are men who believe themselves  _owed_  fellatio but have no interest in the art of cunnilingus, John is  _clearly_  not one of them. After all, Sherlock’s already witnessed the enthusiasm with which John eats Mary out, and he’s sure it’s something he does fairly often.

“Good. Don’t want you forgetting who’s in charge here,” Mary retorts, before giving him a nudge toward the bed. “Go get comfy, love. I draw the line at kneeling on the hard floor.”

Sherlock shivers.


	11. Chapter 11

**Summary for the Chapter:**

> Mary sucks John and makes a suggestion.

**Notes for the Chapter:**

> You are all beautiful creatures for still caring about this fic even though I'm updating horribly slowly.

Unfortunately for Sherlock, John’s new reclining position and Mary’s location between his legs don’t allow for optimal viewing. At least Mary hasn’t gotten started just yet, so Sherlock’s able to awkwardly relocate his chair. John glances his way as he seats himself again and smirks.

“Enjoying your front-row seat?” Sherlock really hopes he learns to stop _blushing_ at every stray innuendo sometime soon, especially if this arrangement turns into something long-term-- as he hopes and suspects it will.

“Oh, quit _teasing_ him, John. You know he’s still knew to this.” Sherlock’s not sure what _this_ is, exactly. Threesomes? Shagging his best friend and his best friend’s wife? _Relationships?_ (To be fair, the latter isn’t quite true, but he tries tries tries not to think of _that_ particular failure too often.)

"It’s fine,” Sherlock interrupts, clearing his throat. He doesn’t want them to think he’s having second thoughts, or that he’s going to fleeing the room. Truthfully, their jokes and banter have made it a little easier for him. It’s when things get too _tense_ and serious that he freezes up. At least, that’s his theory.

“You sure?” Mary’s speaking again, head turned his way though her lips are nearly brushing against John’s shaft. “John and I have been in enough threesomes that we learned not to take any of it too seriously, but I know you…” She trails off, doesn’t quite finish the sentence, for which Sherlock is honestly grateful.

“I’m sure,” Sherlock responds firmly, and he’s graced with one of Mary’s small, genuine smiles. Poor John, meanwhile, is trying not to squirm. He’s clearly still hard, thanks to the proximity of Mary’s mouth to his prick, although he seems to be trying to behave.

“I believe your husband is in need of attention.” Sherlock manages a tone that’s almost light-hearted, close to the way they’ve been talking. He’s rewarded when Mary scoff’s and gives John’s penis a gentle flick.

“I believe my husband won’t claim to _need_ anything, if he knows what’s good for him. But I suppose I could stop teasing him.”

“That would be _lovely_ , thanks.” John sounds a little strained, like he’s _trying_ to stay on Mary’s good side about all this. Apparently it works, because Mary finally wraps her hand around the base of his cock and slides her plush lips down around the head.

“Oh, _Christ_.” Sherlock suspects it’s been a while since Mary did this for John, if only because of the way John’s head falls back as he lets out the breathless swear. Mary doesn’t seem to be doing this half-arsed, either. She’s taking her time, coating John’s shaft with saliva so the hand wrapped around his base can finally start stroking in time with the bobbing of her lips around him.

Sherlock licks his own lips as he watches, a hand straying to his erection to run fingertips lightly along his length. He’s not interested in getting off just yet and doesn’t want to risk tipping himself over the edge too soon, so he simply teases himself for the time being, keeping himself hard as he watches.

The blowjob Sherlock witness is impressive even by his somewhat limited experience. Clearly, John agrees, if the way he’s clutching the sheets, gasping, and giving stuttering thrusts are any indication.

Before the whole thing can end to soon, though, Mary pulls off John’s cock, stroking him in an unhurried way that makes her husband groan.

“ _Fuck_ , Mary,” John gasps. He’s clearly trying not to _whine_ , his hips rocking as if the needy motion can draw her lips back to him.

“Sherlock?” Though Mary doesn’t glance toward him at first, she’s smirking slightly as she continues to stroke John.

“How do you feel about anal? Giving or receiving, I don’t think John would complain about either.”

The groan John gives this time is deep and throaty. Obviously _he_ approves.

Sherlock’s taken by surprise, though, and he licks his lips, glancing toward Mary, then John, as his pulse thrums in his throat. They’re going _fast_ , now, almost too fast. But when he gives himself a moment to consider her offer, he realises that he’s _not_ opposed to taking this new step.

“I’ve… experienced both, though it has been a while. I’m unsure that I could be the receptive partner without working myself up to it for several minutes…”

“Just get over here and fuck me, then,” John gasps. Sherlock blinks. It’s one thing for Mary to inform him that John’s not afraid to bottom, another thing entirely to hear it from John’s mouth.

“Yes, I’ll… erm, I’ll grab the condoms and lube, then,” Sherlock stammers slightly, practically lunging for his bedside table. His hands are shaking slightly as he pulls one of the foil packets from the drawer, fingers clumsier than usual. He doesn’t even realise Mary’s moved away from John until she carefully places one hand over his.

Frowning, Sherlock glances up to an understanding expression.

“May I?” There’s something about Mary’s tone, or perhaps her expression, that makes Sherlock certain she actually _asking_ , not just assuming he’ll be okay with it.

Sherlock only has to consider it for about a quarter of a second, before nodding.

Mary’s slender fingers are calm and confident, just like their owner, as they tear open the condom. She locates the lubricated side effortlessly and rolls the latex barrier down Sherlock’s cock in one smooth motion. No stranger to safe sex, but then, she _is_ a doctor’s wife.

Sherlock’s actually surprised when Mary pulls away as soon as the condom’s on him. Somehow, he’d still thought she’d go in for a kiss, at least. Somehow, she seems to realise that he’s had very little interest or experience with women, and she’s willing to respect that. Sherlock gives her a small smile, and she gives John’s bum a pat, earning a snort from both men.

“So, is it safe to assume I’m not getting blown any more right now?” John doesn’t sound _too_ disappointed, considering Sherlock’s already scooting his way across the bed and sliding a pillow beneath John’s arse.

“Sorry, love. But I think it’s a decent enough trade-off, don’t you?”

Mary’s settled up near John’s head and is stroking his face, even ducking down to press her lips to his. While the Watsons kiss, Sherlock grabs his bottle of lube, but John pulls away to stop him.

“Wait. Gloves.” Why _gloves-- ah._ Stupid. Obvious. Of course John would adhere to the highest standards of protection.

“Yes, of course. I’ll go--”

“Just tell me where you’ve got them hidden and I’ll fetch them for you. I don’t have the heart to make you wander all ‘round the flat with a condom on your cock and everything.” Mary’s eyes sparkle, and Sherlock tries not to blush. Again.

“Laboratory.” Neither bothers to correct him; his kitchen isn’t _really_ a kitchen anymore. “Left of the microscope.”

Mary gives both of them another small smile, kisses John on the lips, then Sherlock on the forehead.

“Try not to have too much fun while I’m gone. I’ll be back shortly.”


	12. Chapter 12

**Summary for the Chapter:**

> John gets buggered. Literally.

**Notes for the Chapter:**

> Holy Martin Freeman's balls, it's a second update within the same week. If anyone's even still reading this lolol. Anyway, have some filthy smutty porn.

There’s absolutely every potential for things to get awkward the second Mary leaves. Were Sherlock currently in bed with anyone else, he’d undoubtedly be _squirming_ with awkwardness right now. But it’s _John_ stretched out before him, reclining with legs crossed and arms behind his head like he isn’t waiting to get buggered.

“Sorry. Shouldn’t be long, though.” Where others might give an apologetic grimace, John just tosses the words out there off-handedly. It’s positively refreshing.

“She’s very… helpful.” _Damn._ So much for not filling the silence with small talk. It’s automatic, really, a social habit he’s been trained into.

Luckily, John just smiles up at the ceiling and makes an affirmative noise. Even more luckily, Mary returns just a moment later.

“Good, so you didn’t manage to light the bed on fire while I was gone.”

Sherlock bristles indignantly.

“I only did that _once_ , and it was an accident, as well John knows, one which happened during a highly important experiment for a murder case--”

“Sherlock, it’s fine.” John’s the one reassuring Sherlock this time around, propping himself up on his elbows then bending forward so he can pull Sherlock in for a soft kiss.

“You know I forgave you for that _ages_ ago.”

Ah. Right. Merely an anecdote of his pre-Fall life with Sherlock shared with Mary, then, not a complaint about him.

“Yes, of course,” Sherlock responds, almost sheepish. Mary smiles, shakes her head, and tosses the box of latex gloves onto the bed.

“Get on with it now, will you? John’s got a quality hard-on going right now, thanks to _me_ , and I really don’t want to watch my hard work waste away.”

Sherlock tries to hide a smile as he reaches for the box of gloves and pulls them on with much less trouble than he’d had with the condom. He finally squeezes a small amount of lube onto his first three fingers and scoots in close enough to press two of them against John’s pucker. Testing.

“Jesus,” John swears. Just that single touch is enough to make his hips twitch, and Sherlock can feel a slight twitch of the muscles around John’s entrance, too. He responds by slipping his first finger inside, a move that draws a low moan of appreciation. A distinct lack of resistance means he can slip his second finger in swiftly enough. When he goes to add a third, John grits his teeth and _growls._

“Stop _mucking about_ and _fuck_ me!”

Sherlock’s only too happy to oblige.

It takes only a couple more seconds for Sherlock to peel off the gloves and toss them toward the rubbish bin. After all, latex corrodes latex when rubbed together, and he needs to add just a _little_ extra lubricant to his condom-clad prick. Thankfully, his erection’s scarcely flagged in the last five minutes, and he only strokes himself a couple times before settling comfortably against John’s hole and pushing inside.

This time, John isn’t the only one who makes a sound of pleasure, though in Sherlock’s case it’s definitely more of a _gasp._ He’d forgotten how _tight_ and _hot_ and _perfect_ another person could feel around him, and he stills with clenched teeth, sweating and clamping stubbornly down on the muscles of his groin. The _last_ thing Sherlock wants is to come embarrassingly soon.

“All right?” John’s voice sounds a little strained, understandably so. He’s hanging onto the sheets for dear life and is clearly trying not to just shove himself down fully onto Sherlock’s cock. Sherlock’s grateful.

“Yes, just… It’s been a while.” Sherlock’s own voice is tight with tension, and he breathes evenly through his nostrils a few times before finally exhaling through his mouth and sinking the rest of the way into John. They practically moan in unison.

“ _Christ_ , Sherlock. Your _cock_ …”

Sherlock would probably respond with something similar, but his ability to think at _all_ coherently, let alone _speak_ , has left him completely. Torn between just savouring the tight sheath of John’s body and rocking his hips, Sherlock finds himself leaning forward so he can give John a long, deep, dirty kiss.

When Sherlock pulls away, his eyes stay glued to John’s face. He wants to memorise each and every twitch of his lips, every flutter of his eyelids as Sherlock pulls out and sinks back into him.

John’s eyes go an impossibly darker shade at Sherlock’s scrutiny, and he makes out a sound that’s barely even human when Sherlock begins to thrust.

Sherlock is, of course, vaguely aware that Mary’s still watching them. His mind’s automatically cataloguing her movements in the corner of his eye, but the _vast_ majority of his attention is reserved for John and John alone.

Sherlock’s thrusts are initially long, slow, and deep, much like the kiss he’d just given John. Both men are breathing heavily, sweating and filling the room with the unmistakable, musky smell of sex. Sherlock feels like he’s drowning in John, like he’s discovered a new drug all his own, and he loves every moment of it.

Still the addict, but hopefully this time Sherlock’s drug of choice won’t wreck him utterly.

Neither man says a word at first. Their eyes are on each other as they move, John pushing himself down to bury Sherlock as deep inside him as possible. But neither of them is superhuman, and they seem to reach some mutual agreement that this steady pace, almost _love-making_ , won’t satisfy them any longer.

When Sherlock withdraws, it’s with a low murmur and tap to John’s hip, indicating he should turn over. Though John actually _whines_ at the sudden emptiness where seconds ago he’d been filled with _Sherlock_ , he obeys, turning onto all fours and spreading his legs wide enough that the pinker flesh of his pucker is _just_ visible.

Sherlock doesn’t tease this time, just grabs John’s hip with one hand and lines himself up with the other to sink swiftly back into him. His cock _just_ brushes John’s prostate on entrance, a fleeting touch that nevertheless makes John jerk and swear and Sherlock _grin._

In the corner of Sherlock’s eye, now, Mary’s touching herself shamelessly.

Perhaps wishing to give Mary a show as much as enjoy the benefits of this new position fully, Sherlock places a hand on John’s upper back and pushes him down into the mattress. Though John grunts, he allows it. _Especially_ because this new modification gives Sherlock _just_ the right angle to hit John’s prostate on at least every couple of thrusts when he starts _pounding_ into him.

John gasps, groans, slides a hand underneath him to desperately wank himself. The sound of flesh against flesh joins the noises leaving both John’s and Sherlock’s mouths, and Mary’s just audible beneath the primal symphony.

Between the way Sherlock’s slamming into him and his own hand on his cock, John topples over the edge first. Sherlock _feels_ the orgasm ripple through John in the the clench of his muscles. He pulls out quickly, yanks his condom off, and jerks himself feverishly. Just as John’s coming down from his climax, Sherlock hits his own peak and paints John’s arse and lower back with cum.

John jerks at the first splash of viscous fluid, then breathes out Sherlock’s voice in a somewhat startled, definitely _aroused_ way.

Mary, unsurprisingly, follows the two of them with her own climax a few seconds later.

“ _Jesus_.” John’s the first to speak after almost two full minutes of heavy breathing. The room’s hot, almost miserably so, and Sherlock’s fairly certain the whole _flat_ must reek of their activities by now.

The laugh that leaves Sherlock’s lips is both breathless and slightly giddy.

“I have _got_ to find me one of them.” Mary’s lips are pulled into a wry, tired smile. Her comment’s directed at John, a jerk of her head indicating that she’s talking about Sherlock.

Even now, Mary’s more than willing to respect Sherlock’s boundaries.


End file.
